To be clear, it's not every image. Maybe about 1-4% depending on the situation. Also, I've seen this happen on the Desktop app AND the mobile app for iOS on my iPad.
What does Adobe do to protect the integrity of my uploads? Do you keep checksums of the file before upload to ensure it's the same one I download later? This is a real dealbreaker for the 1TB storage if I cannot trust the process!
Now instead of getting an icon saying that the image is corrupt, I get a rainbow-like effect over the RAW file in the preview and export.
If I look at what's in LR CC, the RAW file is fine. This is easily verifiable by observing the difference in the SHA1 filehashes.
I used the catalog for years, without problem.
I switched from Canon to Fuji in January, and it started happening. Maybe this is a coincidence.
I get the rainbow effect on random images, in the grid and the develop module.
When I export the image, it is corrupted.
When I preview that raw file in explorer, it is also corrupted.
However when I simply copy that raw file, it is fine! When I import the copy, it is also fine.
I don't understand, because normally Lightroom is not changing the originals...
Part of the raw data is missing. When it was happening 6 months ago, it appears to be a problem getting data from the cloud down to LR Classic CC, which was supposedly fixed, but the new problem is more like you describe, which I think means that more of the data is making it down from the cloud, and enough that LR can render something, but the colors mean that part of the image is not all there. You could try rendering 1:1 previews to make sure it's not just the preview that's corrupted, and if it isn't then I'd say try what the person said near the top:
I have an update - in one example that I found, the image was just corrupted in LL Classic CC. If I "Save to..." from LR CC, then that RAW file is OK.
I think they mean from LR CC on the same computer as LR Classic CC.